bin/run.sh should force IPv4 on Linux systems

There is an issue in the Linux kernel that causes ipv6 to not work correctly with JDK 1.5 and lower. As a result, jbossas does not start by default on Linux unless ipv4 is forced. To that end, run.sh needs updating.

Something like:

if [ "`uname`" = "Linux" ]; then
JAVA_OPTS="$JAVA_OPTS -Djava.net.preferIPv4Stack=true"
fi
fi

So that Linux systems use ipv4